The invention concerns a synchronizing ring of a synchronizing device comprising:
an annular body, a gearing and at least one stop,
the annular body is made of sheet metal and is cone-shaped,
the annular body is delimited by a first end section and a second end section, the first end section having the largest cone-diameter of the cone-shaped annular body and the second end section having the smallest cone-diameter of the cone-shaped annular body,
the annular body comprising on its inner peripheral surface, a friction surface,
the gearing extends from the first end section of the annular body and projects beyond the outer peripheral surface of the annular body, and
the stop is formed integrally on the annular body while being arranged on the outer peripheral surface of the annular body.
Synchronizing rings of the pre-cited type, also called outer synchronizing rings, are generally connected to the synchronizing body of a synchronizing device directly or indirectly by positive engagement. This connection is effected by stops formed on the outer synchronizing ring. As a rule, these stops extend from the ends of the synchronizing ring and are often configured as tabs. Restrictions are imposed on their configuration and orientation by the inherent characteristics of shaping techniques. In these synchronizing rings, the radially outward oriented elements like gearings, tabs or axial stops are situated on the edge with the large cone-diameter. The synchronizing rings are mostly drawn from blanks into cups having a conical outer shape, or are stamped into their conical shape from pre-punched annular blanks. The large cone-diameter is situated on the upper edge of the cup, which edge has a radially outward oriented collar. The small cone-diameter forms the bottom region of the cup. The locking gear and the other aforesaid elements are frequently worked out of the collar. It is also possible to punch or for tabs out of the bottom region. But these can only be oriented inwards in radial direction or axially in the direction of removal from the die because, otherwise, they hinder a smooth removal therefrom.
It is required of modern synchronizing devices that they have a low weight and a small design space requirement. Theoretically, the width of a synchronizing device is only determined by the width of the friction surfaces required for the friction performance. In practice, however, the space required for the elements which effect the positive engagement of the rings with their connecting structures, like the aforesaid tabs, must also be taken into consideration. The axial dimension of a synchronizing device is substantially influenced by the configuration and orientation of such tabs. In the prior art, radially inward extending tabs, and particularly those oriented in axial direction, disadvantageously affect the total width of the synchronizing ring. This means that, in addition to the space required for the friction surfaces, extra space is needed for the stops and their engagement into elements of the connecting structure.
The generic structure of an outer synchronizing ring is described in DE 35 19 811 C2. The width of this ring is determined only by the width of its friction surface. The positive engagement with ambient structures is effected through stops that are formed in the region of the outer crown gear. The stops are formed by tabs that by bending of tongues are oriented in the same direction as the surface of the annular body. The tabs start from the end of the ring having the larger diameter of the cone-shaped ring and their free ends point toward the end of the ring that has the small cone-diameter. During the manufacturing process, these tabs are punched out together with the gearing from the edge of the cup after this has been drawn, and are subsequently bent. If the end with the small cone-diameter points toward the synchronizing ring, positive connections to the synchronizing body can only be realized in such synchronizing rings in a more complex and expensive manner, for example, by providing longer tabs. The longer a tab is, the more difficult it is to position and orient it in an exact manner. The manufacturing work and thus also the manufacturing costs are increased, for example, due to additional calibration.
It is therefore an object of the invention to provide a synchronizing ring which avoids the aforesaid drawbacks and whose width is substantially determined only by the required width of its friction surface.
This object is achieved according to the characterizing part of claim 1 in that the stop is arranged on or near the end section of the annular body having the small cone-diameter, and the contour of the stop extends in radial direction beyond the contour of the outer peripheral surface of the annular body. The stops are preferably arranged on the end of the outer synchronizing ring on which the small diameter of its conical annular body is formed. Starting substantially from the end, these stops protrude in radial direction beyond the outer contour of the annular body. No additional space is therefore required in axial direction in excess of the width of the annular body with its friction surface. Since the stops are already arranged on the end of the synchronizing ring facing the synchronizing body, they can be very short and compact. Their shape and position can be very precisely realized. Their manufacturing can be integrated in the shaping process of the synchronizing ring, or can follow this. It is possible to execute and configure the stops in many different forms.
In a preferred embodiment, the stop is formed by a radially outward oriented tab that extends radially from the end of the annular body. The tab can be made during the fabrication of the synchronizing ring, for example, from the material of the bottom of the drawn cup by stamping and folding it over radially outwards. The material has to be likewise shaped radially outwards even if the tab is made in the blank before this is shaped and the blank is then stamped to form the synchronizing ring with a conical cross-section, or if the synchronizing ring is made from a tubular section. It is also conceivable to form the tabs by radially outward bordering.
According to a further feature of the invention, the stop may also be formed by a tab that is worked at least partly out of the wall of the annular body and then stamped radially outwards. In the region of the annular body, therefore, free cuts or recesses must be provided on the left and right of the material required for making the tabs. This can be of advantage if a stop is required that does not have to be absolutely flush with the end of the annular body in axial direction. Besides this, a recess is created in this way which additionally serves entrainment and guidance purposes for the engagement of connecting elements, for example thrust members, with the synchronizing body.
Additional free cuts on the left and right of the junction of a tab with the annular body are also required for avoiding stress peaks which can result from notch effects under loading.
Larger stop and guide surfaces are created on a stop if, as described in a further preferred embodiment of the invention, the tab comprises on its free end a folded edge oriented towards the gearing. This folded edge may be bent at a slant or at right angles to the tab and points towards the gearing. In this way, enlarged lateral contact surfaces are formed on the stop for contact with the synchronizing body which lead to a reduction of the contact pressure between the stop and the synchronizing body on abrupt entrainment of the synchronizing ring by the synchronizing body.
In an advantageous embodiment of the invention, the sides of the tabs facing away from the gearing form an axial stop surface. This axial stop surface is preferably perpendicular to the central longitudinal axis of the synchronizing ring and extends from the inner diameter of the annular body to the outer edge of the tab. It is also conceivable to have the stop surface extend at an acute or an obtuse angle to the central longitudinal axis of the synchronizing ring.
Further stops according to the invention are preferably made by stamping or shaping of the annular body. Thus, in a preferred embodiment, a stamping is made on the end of the annular body having the small cone-diameter. During stamping, material is displaced out of the wall of the annular body to beyond the outer radial contour for simultaneously forming an axial stop surface preferably extending at a right angle to the central longitudinal axis of the synchronizing ring. In one variant, the stamping is effected on the entire wall cross-section. If it is desired, for example, to keep the shaping forcing low, the stamping is worked out of the surface of the annular body. In this case, a portion of a wall subsists between the inner peripheral surface and the stamping and can be used as a guide element, or it serves to assure that the friction surface configured on the inner surface of the synchronizing ring is not interrupted.
A further advantageous embodiment of a stop according to the invention comprises making the stop by a bead-like formation. This forms on the outer peripheral surface of the annular body, a contour protruding beyond the wall, and on the inner peripheral surface, a groove oriented along the central longitudinal axis of the synchronizing body. The stop surface itself is formed on the end of the formation on its side facing away from gearing of the synchronizing ring. It is of advantage that the groove formed by the formation can serve as an oil groove of the synchronizing ring.
In a further preferred embodiment, stops in the form of tabs are cut free from the wall of the annular body and are bent slightly radially outwards. These tabs are bent outward only so far that their free end forms a stop. That portion of an end surface of the free end that protrudes beyond the contour of the outer peripheral surface of the annular body forms the axial stop surface.